1. Field of the Invention
This invention relates to apparatus for assembling a liner for lining a passage. The passage may comprise a duct such as for example a pipeline, or an underground passage such as for example a tunnel.
The liner may be assembled in a pre-existing passage or it may be assembled during construction or formation of a passage. The liner may be for any appropriate purpose, such as for example to seal a passage against ingress or egress of fluid through the side wall thereof, or to provide internal support to a passage.
2. Background Art
A particular application of the apparatus is in the recovery of material from the ground (including the floor of bodies of water) and in particular from underground locations.
The invention has been devised specifically, although not solely, for underground mining operations including in particular mining operations in continuously collapsing sand environments. In such an application, the invention is concerned with improvements to apparatus disclosed in International Application Nos. PCT/AU96/00106 and PCT/AU95/00667 in the name of Neil Deryck Bray Graham, the contents of which are incorporated herein by way of reference.
In International Application No. PCT/AU96/00106 there is disclosed a system for recovery of materials from underground locations. Specifically, there is disclosed apparatus for recovering material from an underground location, comprising a recovery head for receiving material to be recovered and a conveying means for conveying the material from the recovery head to a remote location. The recovery head comprises a chamber for receiving material to be recovered and a screen associated with the chamber for screening material entering the chamber. The screen has a first side from which material being screened passes therethrough. The screen has a plurality of elongate screen openings which extend from the first side of the screen to a second side. A plurality of tines are mounted on a support means disposed on the second side of the screen, with each tine being movable along a path at least part of which includes one of the elongate screen openings, whereby the tine is received in and movable along the elongate screen opening, with the tine extended beyond the first side of the screen for at least part of the movement thereof along the screen.
Typically, the conveying means comprises a pipe string and the recovery head is positioned at the lower end of the pipe string. A structure for operating the pipe string is provided at a receiving and handling station situated at ground level. The recovery head is delivered to the underground location at which a mining operation is to be performed and also moves through that location by progressively excavating material to create a passage for itself and the pipe string trailing behind it. The difficulty with this arrangement is that the passage excavated by the recovery head can collapse about the pipe string, particularly in circumstances where the surrounding material is unstable, such as in soft sandy conditions.
International Application No. PCT/AU95/00667 discloses an arrangement for progressively installing a lining within the passage created by the recovery head as the passage is formed. The lining comprises a casing defined by a shroud provided about the pipe string to line the passage so as to prevent the surrounding material from collapsing onto the pipe string. The shroud is formed from flexible material delivered in two longitudinal sections and then assembled to form the shroud around the pipe string. Each longitudinal section of flexible material is stored in roll form at a station situated at ground level and is unwound from the roll as the pipes string advances. This arrangement allows the shroud to be deployed over long distances.
As disclosed in International Application No. PCT/AU95/00667, the shroud formed from flexible material is assembled around the pipe string behind the recovery head for lining the passage created by the recovery head so as to prevent material in the surrounding environment from collapsing onto the pipe string. The shroud is assembled from flexible material delivered in two longitudinal sections. The pipe string has a head end section which is provided with two rollers one corresponding to each longitudinal section of the flexible material. Each section of flexible material is delivered to its respective roller in a compact condition and turns about the respective roller to provide an inner section and an outer section. The outer sections spread from the compact condition and are subsequently brought together to form the shroud.
The rollers are accommodated in a casing which surrounds the head end section. Because of their nature, the rollers form protuberances in the casing. Unfortunately, the protuberances have a detrimental influence in that their presence imparts a significant amount of drag on the overall assembly.
The quest for a solution to this problem has led to the present invention.